In small pan, melt second margarine
measure and add flour to create a roux. It should be light brown in
color.

When stock comes to a boil, add roux with a wire whisk.
This will cause the soup to start thickening. Return to a boil. Slowly
add the milk.

If the soup is too thin, make additional roux and
add it to the soup. Make sure to cook the roux until a tan color. This
will get rid of the raw flour taste. If the soup is too thick, thin it
out with more milk.